The present invention relates to a belt drive device and an image forming apparatus having the same.
In an image forming process of a conventional image forming apparatus such as a printer, a copier, and a facsimile, first, a photosensitive member as an image supporting member is charged. Then, an exposure device directly exposes an image, or a laser scanning optical system or an LED (Light Emitting Diode) light writing optical system optically writes an image according to an image signal, so that a static latent image is formed on the photosensitive member. Then, a developing device attaches toner to the static latent image to form a toner image, and the toner image is transferred directly or through an intermediate transfer member to a transfer member such as a transfer sheet and film. After the transfer, the transfer member is transported to a fixing device, so that the fixing device fixes the toner image to the transfer member, thereby obtaining a fixed image.
In the series of image forming process, an image forming apparatus may be provided with a belt member such as a photosensitive belt and an intermediate transfer belt as an image supporting member with a surface where a toner image is formed and transferred thereon, or may be provided with a belt member such as a transfer belt as a transporting member of a transfer member.
In such an image forming apparatus, toner may partially remain on a surface of the belt member after the toner image is transferred or the transfer member is transported, thereby causing various problems. To this end, a belt drive device of the image forming apparatus may be provided with a cleaning blade as a cleaning member for mechanically scraping off and removing toner remaining on the surface of the belt member.
When the image forming apparatus is provided with the belt member, the belt member may run in a winding path due to a degree of parallel arrangement of two rollers, uneven tension of the belt member, or dimensional accuracy of a roller. In order to correct the winding path of the belt member, a belt drive device may be provided with a mechanism for shifting a roller shaft according to a lateral movement of a belt member (refer to Patent Reference)
Patent Reference: Japanese Patent Publication No. 2006-162659
In the conventional belt drive device, a cleaning blade is fixed separately from the belt member. Accordingly, when the belt member shifts to left side or right side, there is an area on the belt member where the cleaning blade cannot clean (non-cleanable area). As a result, if the image forming apparatus continues the operation with the belt member shifted, toner or foreign matter may accumulate in the non-cleanable area. Therefore, toner may scatter in a surrounding area of the belt drive device, thereby making inside the image forming apparatus dirty. Further, foreign matter may stick to a surface of a roller driving the belt member to decrease friction therebetween, thereby driving the belt member unevenly.
In view of the problems described above, an object of the present invention is to provide a belt drive device and an image forming apparatus, in which it is possible to solve the problems in the conventional belt drive device. In particular, it is possible to safely correct a winding path of a belt member.
Further objects and advantages of the invention will be apparent from the following description of the invention.